Nozzle for injecting sublimable solid particles entrained in gas for cleaning a surface

ABSTRACT

Disclosed is a nozzle for injecting sublimable solid particles, which is capable of minimizing consumption of the carrier gas and also maximizing cleaning efficiency. The nozzle comprises a base block having a space in which carrier gas is supplied through a gas supplying pipe; a sub-block having a space in which cleaning medium decompressed by a regulator is supplied through a cleaning medium supplying pipe; a first venturi block having a venturi path for adiabatically expanding the carrier gas supplied from the space of the base block, and a cleaning medium injection path communicating the venturi path and the space of the sub-block and the carrier gas passed through the venturi path; and a second venturi block having a venturi path for adiabatically expanding the mixed gas of the carrier gas and the cleaning medium.

TECHNICAL FIELD

The present invention relates to a nozzle for injecting sublimable solidparticles such as Co₂ snow, Ar snow, etc., to clean a surface of a waferor FPD (Flat Panel Display) and the like.

BACKGROUND ART

In order to clean pollutants such as fine particles on a surface of awafer, an LCD, a color filter or various glass substrates, there hasbeen proposed various techniques. Particularly, in the semiconductorindustry, high-pressure liquid is used independently or used in a stateof being combined with brushes to remove the polluted fine particlesfrom a surface of a semiconductor wafer. These processes achievedpartial success in removing the pollutant. However, the brushes scratchthe surface of the substrate, and also it may generate undesirablestatic electricity. And, the high-pressure liquid is apt to cut the softsurface of the substrate. Further, the high-pressure liquid has adrawback that it is not easy to withdraw the liquid from the brushes andhigh-pressure liquid cleaning system.

Meanwhile, it is well known that solid and gas phase carbon dioxide (CO₂snow) can remove the polluted fine particles from the surface of thesubstrate without the above-mentioned drawback. One of the techniques isdisclosed in U.S. Pat. No. 5,125,979.

In the above mentioned technique, there are provided a small expansionchamber and a large expansion chamber which are communicated with eachother through a venturi interposed therebetween. At an outlet of thelarge expansion chamber is provided an accelerating chamber foraccelerating an injecting speed of a cleaning medium. The cleaningmedium is supplied from a cleaning medium supplying source to the smallexpansion chamber, and then adiabatically expanded while being suppliedthrough the venturi to the large expansion chamber, thereby forming Co₂snow having snow particles of about 46%. The Co₂ snow is accelerated byinert gas introduced to the accelerating chamber, and then injectedthrough a nozzle to a desired position in which the cleaning process isperformed.

That is, in the technique, the cleaning medium is transformed into theCo₂ snow, while passing through the venturi. Then, the particles of theCo₂ snow grow, while the Co₂ snow passes through the large expansionchamber. The cleaning medium injected through the nozzle cleans thepollutant on the surface of the substrate and then sublimed.

However, in the technique, since the cleaning medium of Co₂ istransformed into the Co₂ snow, while passing through one venturi, asolidification rate of the cleaning medium is low. Furthermore, sincethe cleaning process is typically performed at a high presser, there isa problem that a large quantity of cleaning medium is needed to removethe polluted fine particles under the same conditions.

To solve the problem, the applicant had proposed Korean Patentapplication No. 2000-8560 filed on Feb. 22, 2000, entitled “Nozzle forcleaning components of semiconductor fabricating equipment”.

As shown in FIGS. 1 to 3, the nozzle for cleaning components of asemiconductor fabricating equipment has first and second venturi blocks51 and 53, which are disposed in series, to provide a wider cleaningsurface than a single nozzle, thereby maximizing the cleaningefficiency. A carrier gas supplying pipe 61 is connected to a base block55 in which the first venturi block 51 is disposed. A cleaning mediumsupplying pipe 59 is connected to a sub-block 57 disposed at an upperside of the base block 55.

The cleaning medium supplying pipe 59 is connected to a cleaning mediumchamber 13 b in which high-pressure Co₂ is stored in liquid phase. Thecleaning medium supplying pipe 59 is controlled by a regulator 11 tohave a lower pressure of 100˜120 psi. Since the cleaning medium of Co₂is reduced from the high pressure to the low pressure, the particles ofsnow state are formed in the cleaning medium. The cleaning mediumcontrolled to have the above-mentioned pressure is supplied through thecleaning medium supplying pipe 59 and the sub-block 57 to a fan-shapedspace 51 a formed in the base block 55.

The carrier gas supplying pipe 61 is connected to a carrier gas chamber13 a to supply carrier gas such as N₂ to the base block 55. The carriergas is stored in the carrier gas chamber 13 a at a high pressure. Asshown in FIG. 2, at an distal end of the carrier gas supplying pipe 61,there is formed a slot 61 a for uniformly injecting the carrier gas intoa plurality of venturi paths formed at the first venturi block 51. Atthe sub-block 57, there is formed a path 57 a perpendicular to thefan-shaped space 51 a to be communicated with the space 51 a. Thecleaning medium supplying pipe 59 has a circular portion on which thecleaning medium is dashed, so that the cleaning medium is uniformlyinjected into the fan-shaped space 51 a.

Accordingly, the cleaning medium supplied through the cleaning mediumsupplying pipe 59 to the space 51 a of the base block 55 is mixed withthe carrier gas injected from the carrier gas supplying pipe 61 in thespace 51 a so as to firstly induce the solidification of the cleaningmedium. The mixed gas is adiabatically expanded, while passing throughthe venturi paths formed in the first venturi block 51, whereby atemperature and a pressure of the mixed gas are sharply reduced. Sincethe cleaning medium is adiabatically expanded in the first venturi block51, the solidification of the cleaning medium is further promoted.Further, the cleaning medium is adiabatically expanded again, whilepassing through the second venturi block 53, and thus, thesolidification of the cleaning medium is promoted once more. However,the conventional technique as described above has a structure that thecleaning medium supplying path is perpendicular to the carrier gassupplying path at a place where the cleaning medium and the carrier gasis mixed. Therefore, since the carrier gas having the higher pressurethan the cleaning medium is flowed back to the cleaning medium supplyingpath, there is a problem that the cleaning medium supplying path isclogged. Furthermore, since the carrier gas is supplied at the highpressure, there is another problem that the consumption of the carriergas is increased.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to provide a nozzle forinjecting sublimable solid particles, which is capable of preventing theclogging of the cleaning medium supplying path due to backflow ofcarrier gas, and also minimizing consumption of the carrier gas.

Another object of the present invention is to provide a nozzle forinjecting sublimable solid particles, in which a desired staying spacefor carrier gas and cleaning medium is secured at a place that thecarrier gas and the cleaning medium are mixed, thereby uniformly mixingthe carrier gas and the cleaning medium, and which stabilizes growth ofparticles and flow of the carrier gas and the cleaning medium tomaximize solidification of the cleaning medium, thereby improvingcleaning efficiency.

The present invention provides nozzle for injecting sublimable solidparticles entrained in gas for cleaning a surface, comprising a baseblock having a space in which carrier gas is supplied through a gassupplying pipe; a sub-block having a space in which cleaning mediumdecompressed by a regulator is supplied through a cleaning mediumsupplying pipe; a first venturi block having a venturi path foradiabatically expanding the carrier gas supplied from the space of thebase block, and a cleaning medium injection path communicating theventuri path and the space of the sub-block to mix the cleaning mediumof the sub-block and the carrier gas passed through the venturi path;and a second venturi block having a venturi path for adiabaticallyexpanding the mixed gas of the carrier gas and the cleaning medium,wherein the venturi path of the first venturi block has an acute anglewith respect to the cleaning medium injection path.

The nozzle of the present invention comprises an intermediate blockhaving a path, which is disposed between the first and second venturiblocks, for promoting the mixture of the carrier gas and the cleaningmedium in the mixed gas moving from the path of the first venturi blockto the path of the second venturi block and thus inducing growth of snowparticles.

Herein, the first and second venturi blocks respectively have aplurality of venturi paths disposed in parallel, and the sub-block hasthe same number of cleaning medium injection paths as the number ofventuri paths.

Further, the venturi path of the first venturi block has an angle of 15to 60° with respect to the cleaning medium injection path. Therefore, itis prevented that the carrier gas is flowed back to the cleaning mediuminjection path. More preferably, the injection hole in which thecleaning medium decompressed by the regulator is mixed with the carriergas has a diameter of 0.1 to 0.3 mm. Therefore, since the pressure ofthe cleaning medium injected through the injection path is higher thanthat of the carrier gas, it is efficiently prevented that the carriergas is flowed back.

the carrier gas supplying pipe has a slit at an end thereof so that thecarrier gas is injected at a desired angle range when supplied to thespace of the base block. The carrier gas injected through the slit hasan angle of 116°.

further, the cleaning medium supplied to the first venturi path has apressure of 10 to 50 psi, and the carrier gas supplied to the space ofthe base block has a pressure of 60 to 100 psi.

The cleaning medium is Co₂ ⁺ or Ar⁺, and the carrier gas is N₂ gas orclean dry air.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view a conventional nozzle for cleaning acomponent of a semiconductor;

FIG. 2 is an exploded perspective view of the nozzle of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line III—III of FIG. 1;

FIG. 4 is a perspective view of a nozzle for injecting sublimable solidparticles entrained in gas for cleaning a surface according to thepresent invention;

FIG. 5 is an exploded perspective view of the nozzle of FIG. 4;

FIG. 6 is a plan view of the nozzle in which a sub-block is removedaccording to the present invention; and

FIG. 7 is a cross-sectional view taken along the line VII—VII of FIG. 4.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in further detail withreference to the drawings.

As shown in FIGS. 4 and 5, a nozzle according to the present inventionincludes a base block 1, a sub-block 2, a first venturi block 3 and asecond venturi block 4. A intermediate block 5 may be disposed betweenthe first and second venturi blocks 3 and 4. The intermediate block 5has a mixing space for assuring mixture of cleaning medium and carriergas and stabilizing flow of the cleaning medium and carrier gas.

The base block 1 is connected through a carrier gas supplying pipe 12 toa carrier gas chamber 13 a in which carrier gas such as N₂ gas or cleandryd air. The carrier gas supplied to the base block 1 typically has apressure of 60 to 100 psi. The carrier gas supplying pipe 12 has anozzle body 7 at an end thereof. As shown in FIG. 5, the nozzle body 7is disposed at the base block 1 so as to inject the carrier gas into aspace 6 formed in the base block 1. The nozzle body-7 is formed with aslit 7 a for injecting the carrier gas at an injecting angle a of about116° into the space of the base block 1. As shown in FIG. 6, the space 6formed in the base block 1 is formed into a sector having an angle of116°.

The sub-block 2 is positioned at an upper side of the base block 1 to beconnected to the first venturi block 3. The sub-block 2 is connectedthrough a cleaning medium supplying pipe 14 to a Co₂ cleaning mediumchamber 13 b in which cleaning medium for generating solidifyingparticles like Co₂ particles. When the cleaning medium is injectedthrough a nozzle body 9, which is disposed at an end of the cleaningmedium supplying pipe 14, to an injection space 10, the cleaning mediumis firstly decompressed to a pressure of about 10 to 50 psi by aregulator 11 or other valve means disposed at the cleaning mediumsupplying pipe 14 and then injected into the injection space 10 of thesub-block 2 in a liquid C0 ₂ state.

Meanwhile, a cryogenic heat exchanger (not shown) is disposed betweenthe cleaning medium chamber 13 b and the regulator 11. Therefore, thecleaning medium of Co₂ gas is transformed into liquid Co₂ due totemperature drop while passing through the cryogenic heat exchanger, andtransformed again into liquid Co₂ having a lower pressure while passingthrough the regulator 11, and then introduced into the sub-block 2.Solidified particles like Co₂ particles is generated at a place wherethe cleaning medium is mixed with the carrier gas.

As shown in FIGS. 5 and 7, the injection space 10 of the sub-block 2 isformed into the sector, and disposed to be perpendicular to the nozzlebody 9. The nozzle body 9 is positioned at an upper side of the space10. The nozzle body 9 has an arc-shaped distribution surface 9 a at anend thereof so that the cleaning medium injected through a nozzle hole 9b of the nozzle body 9 is injected into a lower portion of the injectionspace 10. Therefore, the cleaning medium injected from the nozzle body 9is dashed on the distribution surface 9 a, and thus injected at an angleof about 146° into the lower portion of the injection space 10. In orderto obtain such injection angle of the cleaning medium, the distributionsurface 9 a has an angle of about 75° with respect to the distributionsurface 9 a.

As shown in drawing, the first venturi block 3 is connected to the baseblock 1 and the sub-block 2. The first venturi block 3 has multiple,preferably, 10 or more venturi paths 15 disposed in parallel andmultiple cleaning medium injection paths 16 for connecting each throttleportion of the venturi path 15 to the injection space 10 of thesub-block 2, such that the cleaning medium injection paths 16 areadjacent to the throttle portion of the venturi paths 15. The venturipaths 15 are connected with the space 6 formed in the base block 1. Thecarrier gas supplied from the space 6 formed in the base block 1 isadiabatically expanded and a flow rate of the carrier gas is increased,while the carrier gas passes through a throttle portion of the venturipath 15. Therefore, in the venturi path 15, the cleaning medium suppliedfrom the sub-block 2 through the cleaning medium injection path 16 tothe venturi path 15 can be rapidly mixed with the carrier gas suppliedfrom the base block 1 to the venturi path 15.

Each of the cleaning medium injection paths 16 has an angle of 15° to60°, preferably 45 ° with respect to each of the venturi paths 15. Theventuri paths 15 respectively have a diameter of about 2 mm at a placewhere the venturi paths 15 are contacted with the cleaning mediuminjection paths 16. The throttle portion formed in the venturi path 15has a diameter of about 0.3 to 1 mm. An inlet and an outlet of theventuri path 15 respectively have a diameter of 1 to 3 mm. However, itis preferable that the diameter of the outlet is smaller than that ofthe inlet. In addition, since the cleaning medium injection paths 16respectively have the above-mentioned angle with respect to the venturipaths 15 and the pressure of the carrier gas is about 10 to 50 psi lowerthan that of the cleaning medium of liquid Co2 state, a cloggingphenomenon of the pipe due to back pressure or solidified particles isprevented.

Meanwhile, the carrier gas can be uniformly supplied to the venturipaths 15 formed in the first venturi block 3 according to a structure ofthe slit 7 a of the nozzle body 7 disposed in base block ion solution,and the cleaning medium can be uniformly supplied to the cleaning mediumsupplying path 16 according to a structure of the distribution surface 9a and the space 10 of the nozzle body 9. The cleaning medium isadiabatically expanded while passing through the venturi paths 15 of thefirst venturi block 3, and the carrier gas has the increased flow rateafter passing through the throttle portion, whereby a mixing rate of thecarrier gas and the cleaning medium is increased. Preferably, thecleaning medium path 16 has a larger diameter of an upper portionthereof than that of a lower portion thereof, and the diameter of thelower portion is 0.1 to 0.3 mm. Therefore, the snow solidification ofthe cleaning medium is improved.

The intermediate block 5 is connected to the first venturi block 3. Theintermediate block 5 has a mixing space 18 and a path 19 communicatedwith a venturi path 17 of the second venturi block 4. The mixing space18 secures the sure mixing of the cleaning medium and the carrier gasand also stabilizes the flow of the cleaning medium and the carrier gasso as to induce the growth of the snow particles. In the mixing space18, a turbulent flow is stably transformed into a laminar flow, whilethe carrier gas and the cleaning medium are completely mixed and, at thesame time, the snow particles are grown, thereby maintaining the uniforminjection conditions. Preferably, each of the paths 19 has the samediameter as an inlet of the venturi path 15.

The second venturi block 4 has the same number of venturi paths 17 asthe number of venturi paths 15 of the first venturi block 3 and thenumber of the paths of the intermediate block 5. The second venturiblock 4 is connected to the intermediate block 5 so that the venturipaths 17 are exactly met with each other. As described above, sincethere are provided 10 or more venturi paths 17 of the second venturiblock 4 through which the mixture of the cleaning medium and the carriergas is injected into the outside, the nozzle of the present inventionhas an increased injection surface area.

The mixed gas of the cleaning medium and the carrier gas, of which thesnow particles are grown, is adiabatically expanded again, while passingthrough the venturi paths 17 of the second venturi block 4. Thus, a sizeof the sublimable solid particle can be maximized.

Meanwhile, in the embodiment of the present invention, as describedabove, the intermediate block 5 is disposed between the first venturiblock 3 and the second venturi block 4. Further, since the diameter ofthe cleaning medium path 16 through which the cleaning medium of theliquid Co₂ state is passed is reduced, the pressure of the cleaningmedium, which is higher than the supplying pressure of the carrier gas,is applied to the cleaning medium path, thereby solving the problem ofback pressure. Furthermore, since a proper amount of snow particles areformed, it is possible to inject the cleaning medium with the lowpressure carrier gas.

As described above, the mixing places of the paths 15, 16, 17 and 19formed in the first and second venturi block 3 and 4 and theintermediate block 5 respectively have a diameter of 2 mm. The throttleportion of each venturi path 15 and 17 has a diameter of 0.3 to 1 mm.The cleaning medium path 16 has a diameter of 0.1 to 0.3 mm. The inletand outlet have a diameter of 1 to 3 mm.

According to the nozzle of the present invention, at the place in whichthe cleaning medium and the carrier gas are mixed, the cleaning mediumsupplying paths have an acute angle with respect to the venturi paths.The clogging of the cleaning medium supplying path due to the backflowof the carrier gas is prevented by pressure gradient according to a sizeof the cleaning medium path.

In addition, due to the first and second venturi blocks and theintermediate block, the flow and the solidified particles of thecleaning medium are stabilized and the solidification rate is maximized.Therefore, the consumption of the cleaning medium can be reduced, whilea time of cleaning process can be remarkably reduced by the increasingin the injection surface area of the nozzle.

INDUSTRIAL APPLICABILITY

As described above, the cleaning medium is transformed into the liquidCo₂ by the first decompression using the regulator and other valve andthe temperature drop using the cryogenic heat exchanger. The liquid Co₂is phase-changed to form the sublimable solid particles like the Co₂particles, while passing through the cleaning medium path 16. Further,while the cleaning medium is passed through the nozzle of the presentinvention, an opportunity of the adiabatic expansion of the cleaningmedium is maximized, and the flow rate of the cleaning medium isincreased by the carrier gas. Meanwhile, in the embodiment, the Co₂ isused as the cleaning medium. However, it is obvious to those skilled inthe art that other medium like Ar⁺ can be used as the cleaning medium.

1. A nozzle for injecting sublimable solid particles entrained in gasfor cleaning a surface, comprising: a base block having a space in whichcarrier gas is supplied through a gas supplying pipe; a sub-block havinga space in which cleaning medium decompressed by a regulator is suppliedthrough a cleaning medium supplying pipe; a first venturi block having aventuri path for adiabatically expanding the carrier gas supplied fromthe space of the base block, and a cleaning medium injection path isadjacent to a throttle portion so as to connect the throttle portion ofthe venturi path with the space of the sub-block to mix the cleaningmedium of the sub-block and the carrier gas passed through the venturipath; a second venturi block having a venturi path for adiabaticallyexpanding the mixed gas of the carrier gas and the cleaning medium,wherein the venturi path of the first venturi block has an acute anglewith respect to the cleaning medium injection path, and wherein thefirst and second venturi blocks respectively have a plurality of venturipaths disposed in parallel, and the sub-block has the same number ofcleaning injection paths as the number of venturi paths.
 2. The nozzleof claim 1, further comprising an intermediate block having a path,which is disposed between the first and second venturi blocks, forpromoting the mixture of the carrier gas and the cleaning medium in themixed gas moving from the path of the first venturi block to the path ofthe second venturi block and thus inducing growth of snow particles. 3.The nozzle of claim 1, wherein the venturi path of the first venturiblock has an angle of 15 to 60° with respect to the cleaning mediuminjection path.
 4. The nozzle of claim 1, wherein the carrier gassupplying pipe has a slit at an end thereof so that the carrier gas isinjected at a desired angle range when supplied to the space of the baseblock.
 5. The nozzle of claim 4, wherein the carrier gas injectedthrough the slit has an angle of 116°.
 6. The nozze of claim 1, whereinthe cleaning medium supplied to the first venturi path has a pressure of10 to 50 psi, and the carrier supplied to the space of the base blockhas a pressure of 60 to 100 psi.
 7. The nozzle of claim 1,wherein thecleaning medium is CO₂ ⁺ or Ar⁺.
 8. The nozzle of claim 1, wherein thecarrier gas is N₂ gas or clean dry air.